In a real-time system, the use of a scratchpad memory can mitigate the difficulties related to analyzing data caches, whose behavior is inherently hard to predict. We propose to use a scratchpad memory for stack allocated data. While statically allocating stack frames for individual functions to scratchpad memory regions aids predictability, it is limited to non-recursive programs and static allocation has to take different calling contexts into account. Using a stack cache that dynamically spills data to and fills data from external memory avoids these problems, while its simple design allows for efficiently deriving worst-case bounds through static analysis. In this paper we present the design and implementation of software managed caching of stack allocated data in a scratchpad memory. We demonstrate a compiler-aided implementation of a stack cache using the LLVM compiler framework and report on its efficiency. Our evaluation encompasses stack management overhead and impact on worst-case execution time analysis. The state-of-the-art worst-case execution time analysis tool aiT is able to correctly classify all stack cache accesses as accesses to the scratchpad memory.

ISBN:

9781450347877

Type:

Konference-paper

Sprog:

Engelsk

Udgivet i:

Proceedings of the 24th International Conference on Real-time Networks and Systems (rtns'16), 2016, p. 319-326